Last night a friend commented how surprised he was that, everywhere he went in Madison, he ran into someone he knew. "I've only been here a little over a year, and that never happened to me in Boulder."
This difference in casual encounters didn't surprise me. From what he had told me, the city of Boulder is an expensive place to live, so many people actually live in one of the surrounding communities. As a graduate student, he had commuted to campus and back to his house every day. He took the bus much of the time, but many other people drive. So despite the fact that Boulder and Madison are often compared - medium sized cities with large universities, liberal politics, and residents with a strong interest in the outdoors, physically active lifestyles, and the environment - they are really very different when viewed through the lens of a "community."
Here in Madison, the people that my friend and I would naturally socialize with: academics, people involved in politics, activists, employees and volunteers at non-profits, etc. live not only in the city, but close to downtown. Because of the geography of the Isthmus, many of us walk, bike, or take the bus for our daily commute and other local trips. We socialize, shop, and play close to home and work because opportunities to do these things are available where we live and work.
So as we go about our daily lives, we are in close proximity to others that we would know anyway. Add in the fact that we tend to travel in ways that allow us to greet and talk - it is far easier to stop and talk when walking or biking than when driving - and you have a higher chance that you will both see someone you know and be able to chat when you do catch sight of that person.
Driving naturally divides people. You are enclosed in a metal box and traveling at a speed and distance from each other that doesn't allow one to yell out, "Yeah, Sue! Where are you going?" You can't discover that you are each looking for a bite to eat or thinking about seeing a movie. You don't have the chance to stop and ask your neighbor what that lovely flower is he has in the yard.
So both the (relative) affordability and the de-emphasis on car travel means that in Madison we are always running into people we know, whether that be a work colleague, a friend-of-a-friend, another parent from your child's school, or just that person that goes to the same coffee shop as you.
These casual encounters are what build and maintain a community. They make people feel safe and reinforce the idea that we share a common life. Although they may not come up with this example, it's what makes small town life so appealing. And yet you don't have to live in a small town to get it. Just start walking, shopping locally, and keeping your eyes open for other people.